'89 taurus poor mileage

My dad's '89 taurus with 46k is getting 16 mpg. It's the 3.0 6cyl. I was wondering if it has o2 sensor(s) His Chilton's book has a section on it, but doesn't say where it is and I can't find it anywhere. I'm assuming it'll be just before or after the converter, but maybe it's hidden under something? Directions?

Your dad's '89 should have two O2 sensors, one for the front cylinder bank and one for the rear bank. They will probably be mounted in the exhaust manifolds near the point where the three runners collect.

Poor fuel economy could be related to more than just the O2 sensors, although O2 sensors are not a bad item to replace anyway with that mileage. You may as well check the spark plugs and wires as well. Also, don't rule out the thermostat and coolant temperature sensor.

I believe the '89 uses a Manifold Absolute Pressure (MAP) sensor rather than a Mass AirFlow (MAF) sensor. The MAP sensor (or MAF) could cause a decrease in fuel economy as well. I would also suggest you add a bottle of fuel injector cleaner to the fuel tank if he doesn't use that regularly. I suggest a bottle in the tank at every oil change as preventive maintenance.

-Rod